Ink-jet printers offer a low cost, high quality, and comparatively noise-free option to other types of printers commonly used with computers. Such printers employ a resistor element in a chamber provided with an egress for ink to enter from a plenum. The plenum is connected to a reservoir for storing the ink. A plurality of such resistor elements are arranged in a particular pattern, called a primitive, in a printhead. Each resistor element is associated with a nozzle in a nozzle plate, through which ink is expelled toward a print medium. The entire assembly of printhead and reservoir comprise an ink-jet pen.
In operation, each resistor element is connected via a conductive trace to a microprocessor, where current-carrying signals cause one or more selected elements to heat up. The heating creates a bubble of ink in the chamber, which expels ink through the nozzle toward the print medium. In this way, firing of a plurality of such resistor elements in a particular order in a given primitive forms alphanumeric characters, performs area-fill, and provides other print capabilities on the medium.
Many ink-jet inks, when printed in various colors or in black on bond paper, copier paper, and other media, can lead to smudge and smearing. Smearing occurs as the still wet or damp ink is touched by something while on the surface of the paper being printed. Smudging is generally associated with a person brushing against or touching the ink while damp. The ink is invariably "smudged" by the touching and leaves traces elsewhere on the page and on the person who touched it.
Prior solutions to smear and smudge have largely involved the use of oxidative drying with the help of catalysts. However, print quality, drop ejection, and long term storage are also important; hence, alternate smudge and smear control mechanisms are needed.
While each of the above has produced varying degrees of success, a need still remains for ink compositions for use in ink-jet printing which do not evidence smearing or smudging, as defined herein, when printed on plain papers, and yet which possess relatively long shelf life and other desirable properties of such inks.